The Train Moves On!

Progress is happening. Much of it reworking what I already did. End of year projects crept in and put this project on the back burner for a couple of weeks. But despite the delay, the train moves forward! And what once was done is now redone!

Servo Motors

For example, the servo motors. The first version worked, sort of. They didn’t move a full 180°, and they were kind of weak.

So I found new motors, bought a couple, and tested them out. That of course, required recreating the servo gear and the whole housing unit.

After many iterations of the servo gear…

I dialed in the tolerances and sizing so the new servo horn/arm fits and stays in place. But just to be safe, I’ll be screwing in each of the servo gears.

Holder

The new servo motor is bigger than the previous. That means the holder needs altering. Fortunately, I designed it measurements so that a quick change of a few select dimensions and the holder fits the new motor snug, but not as tight as a fat kid in the middle seat. Hence the screw.

Also note that I started writing the version number on the object.

I also opened up the back side so it is easier to install the gears, especially the servo gear. I tightened up the tolerances here, too.

(New version on the left.)

And here’s the new gear train all assembled with the new servo. It moves so much more cleanly and smoothly.

And just for fun, here are most of the parts I 3D printed so far.

Moving On

This got me to the point of creating the states. I first needed to calculate how big this project was going to be more accurately.

So I counted all of the hexagons horizontally, and vertically to get a much better calculation than we had used in the past.

I plugged these numbers into a spread sheet, and iterated over a few hexagon dimensions in order to see how big this map can be, or how small it needs to be. Two factors weighted the dimensions the most: 1) the maximum size that the laser cutter can cut, 2) the size of a doorway. I figure that I can cut the map out in multiple pieces, so the size of the laser cutter is not too much of an issue. But if this thing needs to travel, then it definitely needs to fit through a doorway. So that is really the limiting factor, because it will need to travel at some point in it’s existence.

Our original dimensions called for a map that was nearly 4 feet by 3 feet. Too large for the laser cutter, and too large to fit through a door.

A good size ended up being a hexagon that is 20mm from side to side, which creates a map about 30 inches long and 23 inches wide. A common, indoor doorway in the US is 30-32 inches wide. Such a table will definitely slide through at 23 inches wide.

All posts in this series:

• Part I - Critical Making Project 2026
• Part II - Jump on the Gear Train
• Part III - Gear Train Assemble
• Part IV - Back on the Train

Funding provided through a generous grant from UVA Arts Council.